How to play Call of Duty 5 Co-Op ?

When i try to start CO-OP with my friend on LAN…than appears somethnig like cd-key in use. But i’ve different cd key and my friend either. And i dont know what to do now PLS help me
Answer #1
its because yours // or friends game is pirate version there getting smart with the duplicate users even if lan
wait till there cracked servers available
Answer #2
RELOADED needs to release a new crack to rid of the cd-key check..